Behind schedule with coop!

I was planning to have my coop built two weeks ago, but illness, weather, etc have caused delays. We have 4 chicks 4 - 4 1/2 weeks. As I wrote in another post different stages of development one mostly down, one mostly feathers... They are flying around the brooder box (2 x 2 x 5') and I feel like I've got to get them somewhere bigger and better!
So I think I should build a "tractor" and put if out on warm days (possibly with a lamp run out if the temp is less than 75° during the day) and bring the tractor into the garage at night (with heat lamp as garage is cool). Later I can use the tractor in my garden or as an isolation pen.
This will get me time to build the coop the way I want to.
Does that sound like something that will be ok to do?
My big concern are predators. We have EVERYTHING, really EVERYTHING.
I have seen that most tractors do not have wire floors in the run part. I would like the chicks to be able to scratch and peck at the ground but I am afraid that some critter will crawl under the edge and attack them.
Would it be horrible to have a hardware cloth floor in the tractor?
In the permanent coop I am planning a deep litter run with a deeply buried wire perimeter.

Sorry if these questions are obvious but I really appreciate just sounding out other chicken owners on this forum!

Oh, I hear you on the "behind building the coop" thing! My first chicks are 10 weeks old now--I kicked them outside into a 10x10' dog kennel two weeks ago when they started flying all over the brooder room.

A tractor sounds like a fine idea. I would also put hardware cloth on the bottom. Would be heartbreaking to have raised them this far just to lose them now.

I hate to say it, but I have not yet got this built!
I am going to TRY to do it Tomorrow. It would help me (since I am new to chickens) to know if a size something like a 2' x 4' x 2 1/2' high enclosed area with an attached 4' x 4' x 2 1/2' wire enclosed area would work for 2-3 weeks until I can get the permanent coop built.
I am also worried about them getting their toes caught in a wire mesh bottom, but don't want predators to get them either. I'm thinking I'll put shavings in the run over the wire. Thanks for any help!